B Exam Practice Questions And Correct

Commercial Driver’s License (CDL) Class B Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the maximum allowed weight for a single axle on a standard

commercial vehicle?

• 15,000 lbs
• 20,000 lbs
• 22,000 lbs
• 25,000 lbs

Rationale: Federal regulations limit the maximum weight on a single

axle to 22,000 lbs to prevent excessive road wear.

2. When backing a commercial vehicle, the safest method is to:

• Use only mirrors
• Rely on spotters exclusively 1 / 4

• Back slowly and use a spotter if available
• Speed up to minimize time in reverse

Rationale: Backing slowly reduces the risk of accidents and using a

spotter helps avoid blind spots.

• What is the purpose of a pre-trip inspection?
• To clean the vehicle
• To ensure the vehicle is safe to operate
• To check fuel efficiency
• To check the radio and entertainment system

Rationale: A pre-trip inspection identifies potential safety hazards

before operating the vehicle.

• What does a “low air pressure warning” indicate?
• Engine overheating
• Tire underinflation
• Brake system air pressure is too low
• Transmission issue

Rationale: Air brakes rely on sufficient pressure; low pressure can

lead to brake failure.

• Which fire extinguisher type is suitable for electrical fires in a vehicle?
• Water
• Foam
• Class C
• Class A 2 / 4

Rationale: Class C extinguishers are designed for electrical fires to

prevent electrocution.

• What is the minimum tread depth required on drive tires?
• 2/32 inch
• 4/32 inch
• 6/32 inch
• 8/32 inch

Rationale: Federal regulations require at least 4/32 inch tread on

drive tires for safe traction.

• What should a driver do when approaching a railroad crossing with no

signals?

• Accelerate to cross quickly
• Slow down, look both ways, and be prepared to stop
• Stop only if a train is seen
• Sound the horn and proceed

Rationale: Uncontrolled crossings require the driver to be vigilant

and prepared to stop.

• How often must a commercial driver inspect their brakes?
• Once a month
• Before each trip
• Every 1,000 miles
• Every 6 months 3 / 4

Rationale: Federal regulations require drivers to inspect brakes

before each trip for safety.

9. When driving in fog, the safest lights to use are:

• High beams
• Low beams
• Hazard lights only
• Fog lights only

Rationale: High beams reflect off fog and reduce visibility; low beams

improve visibility.

• What does the “gross vehicle weight rating” (GVWR) indicate?
• The empty weight of the vehicle
• The maximum weight the vehicle can safely carry, including cargo

and passengers

• The maximum cargo weight only
• The maximum axle weight

Rationale: GVWR includes the vehicle’s weight plus passengers and

cargo.

• How much space should you maintain behind a vehicle in front

on dry roads?

• 1 second
• 2 seconds
• 4 seconds
• 6 seconds
• / 4